The Pantheon. The Pantheon' was built by Agrippa in 27 B.C., and with the thermae, stagnum, and Euripus formed the group of monuments which he constructed in this part of the campus Martius. This temple contained the statues of many divinities, among them those of Mars, Venus, and the deified Julius, and was probably dedicated particularly to these ancestral deities of the Julian family. Statues of Augustus and Agrippa himself stood in the pronaos. The Pantheon was burned in 80 A.D.; restored by Domitian; struck by lightning and again destroyed about 110 A.D.; rebuilt by Hadrian; and again restored by Severus in 202 A.D. On the frieze of the pronaos of the existing structure is the inscription M. AGRIPPA L. F. TERTIVM FECIT, and on the architrave below, another inscription recording the restoration by Severus and Caracalla. In conqequence of the first of these inscriptions, the present structure was regarded until very recently as the original building of Agrippa, restored but not greatly changed by later emperors; but the investigations carried on in 1892 by Chedanne have proved this belief to be entirely erroneous. The discovery of bricks of Hadrian's time in every part of the edifice proves conclusively that it was wholly constructed between the years 120 and 124 A.D.

The building consists of three parts, the rotunda or drum, the vestibule, and the pronaos. The rotunda is an enormous circular structure, containing a single hall. The walls, which are 6.20 meters thick, support a vast dome, at the top of which is a circular opening 9 meters in diameter, through which light is admitted. The inner diameter of the drum is the same as the height. from the pavement to the opening in the dome, 43.50 meters. Directly opposite the entrance, and in the middle of the east and west sides, are semicircular niches, and between these are square niches making seven in all besides the entrance. An entablature runs round the hall, supported by pilasters flanking each niche and by marble Corinthian columns in front of the niches. Between the niches are rectangular projections flanked by small columns, which have been converted into altars. The pavement is composed of slabs of granite, porphyry, and colored marbles, and the walls of the hall were once covered with magnificent marble linings. The ceiling of the dome is coffered and was originally gilded.

The walls are built of brick and brick-faced concrete, with a somewhat complicated system of brick relieving arches. Thus above each niche in the perpendicular wall is an arch spanning the entire width of the niche, resting on the piers on each side of the niche and reaching nearly to the impost of the dome. This arch is composed of three concentric rings of brick (tegulae bipedales) and extends through the whole thickness of the wall. Beneath each of these arches are three small flat arches, and beneath them three others still smaller and flatter. Within the space of each large arch are two walls of brick, perpendicular to the circumference of the drum. This method of construction serves to distribute the vast weight of the dome.

The investigation of the dome itself has been carried as far as the second row of coffers, and has shown that it is constructed of horizontal rings of brick, constantly diminishing in diameter, and of a series of arches which correspond to those just described. The walls of the drum rest upon foundations of concrete, which project 15 centimenterss beyond the drum on the outside and 70 centimenters on the inside. This foundation is itself surrounded on the outside by a ring of opus reticulatum, which is thought by some to be earlier than Hadrian's building and perhaps to have belonged to the thermae of Agrippa.

The vestibule, 34 meters wide and 7.40 deep, is connected with the rotunda, rests upon the same foundations, and was built at the same time. In front, on each side of the are semicircular niches, which formerly contained the statues of Augustus and Agrippa. These niches are flanked with Corinthian pilasters, and above them runs a double frieze with reliefs of garlands and candelabra. The threshold of the rotunda is an enormous slab of Porta santa marble; but the bronze doors date from the sixteenth century. The exterior of the building is faced with small triangular bricks, with courses of tegulae bipedales at regular intervals, and is divided into three zones by cornices. In the central zone are sixteen sham windows. This whole surface of the drum and the vestibule was covered with marble and stucco, while that of the dome was covered with tiles of gilt bronze.

The portico or pronaos is rectangular, 34 meters wide and 13.60 deep, and has three rows of columns, eight in the front row and four in the second and third, making sixteen in all. These columns are of red and gray granite, 12.50 meters in height and 1.50 in diameter, and are surmounted by Corinthian capitals of white marble. Two of those now standing at the east end of the portico were taken from the thermae Alexandrinae and set up by Alexander VII in 1662, to replace two of the original columns which had been injured. These columns support an entablature and a triangular pediment, which was adorned with reliefs and statues. The inscriptions on the frieze and architrave have already been mentioned. The entablature is continued on both sides of the portico and vestibule as far as the wall of the drum, thus cutting the central zone of the latter directly in the middle. The pavement of the portico is composed of slabs of Egyptian granite. There is no connection between the portico and the main structure, but an open space 55 millimeters wide, and the foundations of the portico were built after those of the rotunda. It is therefore certain that the portico was built after the rest of the structure, but probably immediately afterward, for its construction dates from Hadrian's time and we can hardly conceive of the rotunda and vestibule standing by themselves with no proper front. The roof of the portico was supported by a system of trusses and was ornamented with gilding. The columns rest upon two sorts of foundation; those of the second and third rows upon parallel walls of concrete of Hadrian's time, and those of the front row on a travertine wall which belonged to an earlier rectangular structure, 43.76 meters wide and 19.82 deep, the short axis of which coincides with the north-south axis of the rotunda. This travertine wall, being longer than the width of the portico, projects beyond it on each side, and could have supported ten instead of eight columns. The side wall on the west can be traced, and is 19.82 meters long. These walls belonged to a travertine and peperino podium; and surrounding them, at an average distance of 1 meter, was a marble stulobate. The space between the stylobate and the podium appears to have been filled with rubble. On the south side of this early building was a projection -- eveidently a pronaos -- 21.26 meters wide, showing that the building was a temple fronting south, in form similar to the temple of Concord, much wider than deep, with a pronaos which did not extend across the entire front. The level of this travertine podium is about 2.50 meters below the present pavement of the portico.

Beneath the pavement of the rotunda, at a depth of 2.15 meters, there is an earlier pavement, consisting of a bed of rubble on which were laid slabs of marble, of which fragments of pavonazetto and giallo antico have been found. This pavement extends everywhere under the rotunda, and originally covered a greater area, for it was cut off when the circular foundations of the drum were laid. It is highest in the middle and slopes away in all directions, a condition which is probably due to the great pressure of the wells of the drum. There are no traces of walls crossing this pavement, and therefore it is probable that it was the pavement of an open area, in front of the earlier structure which is beneath the portico. Traces of a third pavement have been found beneath that just described. The marble pavement has also been found under the portico, between the travertine podium and the present pavement.

The result of these discoveries is to show that the existing Pantheon is entirely the work of Hadrian, and that it was built over an earlier building, which is probably the Pantheon of Agrippa, restored by Domitian. The presence of the inscription recording Agrippa's building may be explained by the statement of Hadrian's biographer that that emperor never inscribed his own name on monuments which he restored, but always the name of the original builder, with but one exception. The inscription may therefore be either the original one of Agrippa, preserved through the vicissitudes of one hundred and fifty years, or one cut by Hadrian.

The restoration by Severus was probably confined to a redecoration of the interior. Portions of this marble ornamentation existed until the eighteenth century, when the present system was substituted. The gilt tiles of the roof of the dome were carried off by Constans II, and the bronze trusses and roof of the portico were converted into cannon by the Barberini Pope, Urban VIII, in 1625.

In 609, Boniface IV brought to the Pantheon the bones of several hundred martyrs from the catacombs, and dedicated the temple as the church of S. Maria ad Martyres. In later times it has been known as S. Maria Rotonda, and has been made the burial place of the kings of Italy.

In front of the Pantheon was an open space surrounded by the usual porticus, which extended north as far as the present via delle Collegio, and via del Collegio, and on the east and west coincided with the line of the modern houses. Its columns were of gray granite, and its level somewhat below the present. Flights of five steps led from the portico of the Pantheon to the travertine pavement of this area. Some fragments of pavement and columns have been discovered.
(Platner)

I have decided to put together a critical essay regarding my interpretations and disputations of the contemporary existing texts on the Ichnographia. It will be called "Points of Departure"...

...this combined presentation technique may also follow Piranesi's methodology, thus offering the possibility of a further "re-enactment".

In thinking of the typologies... ...regard to Tafuri's comments of the Ichnographia being a sample book and something unknowable. ...the [scale] comparison between St. Peter's and the Bustum Hadriani is a perfect place to start, although I could also compare the Ichnographia plans to other ancient Roman plans, particularly the large baths. Such drawings would refute Tafuri's and Bloomer's statements regarding the smallness (and seemingly insignificantly treated Pantheon and tomb of Hadrian).

...Piranesi's cribbing of the Porticus Aemilia for the Septa Julia may actually represent Piranesi's scale for the entire Ichnographia. It could be that Piranesi very purposefully installed the Forma Urbis fragment of the Porticus Aemilia into the Ichnographia for the precise purpose of demonstrating more of the actual scale (and gigantism) of ancient Rome (--it is as if Piranesi is here illustrating his own quote about how one just has to look around at Rome and Hadrian's Villa to see the examples he emulates.) Piranesi was not being deceptive or misleading, nor was he acting out of ignorance of the fragment's true identity. Piranesi used the Porticus Aemilia as evidence and example.

The Porticus Alexandri Severi, like the Porticus Vipsania and the Naumachia Domitiani, is one of the buildings along the Ichnographia's Equiria that represents an actual ancient Roman building, however Piranesi situates the Porticus Alexandri Severi much further north than its true historical location. According to Lampridius, "Alexander also began the Basilica Alexandrina, situated between the Campus Martius and the Saepta of Agrippa, one hundred feet broad and one thousand long and so constructed that its weight rested wholly on columns; its completion, however, was prevented by his death." This ancient account places the real "Porticus Alexandri Severi" within the immediate area of the Pantheon, a location far south of Piranesi's positioning of the porticus at the northern end of the Equiria. Piranesi's design and dislocation of the Porticus Alexandri Severi bears a firm symbolic significance within the overall scheme of the Ichnographia Campi Martii, however.

Hi Sue, as promised the following is some data retrieved from my collected xeroxes of material pertaining to the Campo Marzio, which may be useful to your present work regarding Piranesi and the Pantheon.

1. Samuel Ball Platner in The Topography and Monuments of Ancient Rome (1904) gives a concise description of the: Basilica Matidiae, basilica Marcianae. These two basilicas were between the Pantheon, the north end of the Saepta, and the column of Aurelius. One of them was named from Matidia, the mother-in-law of Hadrian, and the other from Marciania, the sister of Trajan. They probably formed one group with the temple of Hadrian. Some cipollino columns that have been found just north of the via dei Pastini, between the Pantheon and the vicolo della Spada d' Orlando, undoubtedly belong to one of them.

2. The book on Hadrian I mentioned is:
Anthony R. Birley, Hadrian: The Restless Emperor (NY: Routledge, 1997). Chapter Two, "The Campus Martius" is all about Hadrian's architecture/building activity within the Campo. One illustration is of a reconstruction of the "South Building" once attached(?) to the south of the Pantheon. The plan of this building matches the 'Xystus' Piranesi delineates within the Ichnographia. The "South Building" is often referred to as the Basilica Neptuni, and, for the record, Piranesi positioned the Basilica Neptuni somewhere else within the Ichnographia, that is, just east of the large sundail.

3. According to Freund's Latin Dictionary: xystus
- among the Greeks, a covered portico or gallery, where athletes exercised in winter
- among the Romans, an open colonnade or portico, or a walk planted with trees, etc., for recreation, conversation, philosophical discussion, etc.

4. I made a cursory overview of Aitken's thesis and I found no direct mention/analysis of the Pantheon complex within the Ichnographia, nor did there seem to be any mention within Aitken's treatment of the Campo Marzio text that Piranesi intended to publish a separate volume on the Pantheon.